Suchergebnisse

Human-induced afforestation has been one of the main policies for environmental management of farmland abandonment in Mediterranean areas. Over the last decades, several studies have reviewed the impact of afforestation activities on geomorphological and hydrological responses and soil properties, although few studies have evaluated the effects on water table dynamics. In parallel to human-induced afforestation activities, natural revegetation occurred in abandoned fields and in fields where the intensity of human activity declined, driving the expansion of shrubs. This research addresses the spatial and temporal variability of water table dynamics in a small afforested sub-catchment located in the Central Spanish Pyrenees. Differences between afforestation (Pinus nigra and Pinus sylvestris) and natural plant colonization (shrubs, mainly Genista scorpius, Buxus sempervirens, and Juniperus communis) and early abandoned meadows (G. scorpius), are analysed in terms of runoff generation and seasonal water table depth dynamics. Precipitation, runoff and water table datasets recorded for the 2014–2019 period are used. Results show a high temporal and spatial variability with large fluctuations in discharge and water table. Groundwater dynamics varied markedly over the year, identifying a wet and dry period with different responses suggesting different runoff generation processes (Hortonian flow during dry and wet periods, and saturation excess runoff during wet conditions). Furthermore, important differences are noted among the various land cover types: (i) in the natural revegetation area (shrubland and meadows) a marked seasonal cycle was observed with short saturation periods during winter and spring; and (ii) in the afforestation areas, the water table dynamics showed a seasonal cycle with a high variability, with fast responses and rapid oscillations. Likewise, the relationship between the depth of water table and hydrological variables was not straightforward, suggesting complex hydrological behaviour. ; This work was funded by the H2020-MSCA-IF-2018 programme (Marie Sklodowska-Curie Actions) of the European Union under REA grant agreement, number 834329-SEDILAND, and by the MANMOUNT project (PID2019-105983RB-I00/AEI/10.13039/501100011033, funded by MICINN-FEDER). ; Peer reviewed

16 Pags. This article as a Preface by the Editors belonging to a special issue of Catena titled "Geoecology in Mediterranean mountain areas. Tribute to Professor José María García Ruiz". The definitive version is available at: http://www.sciencedirect.com/science/journal/03418162 ; The origin of this special issue arose from a scientific meeting held in Logroño (Spain) in October 2014, under the theme Geoecology in extreme environments: mountains and semiarid areas ( Arnáez et al., 2014). The main motivation of the event was to recognise, on the occasion of his retirement, the outstanding contribution of Prof. José María García-Ruiz to the progress of Geoecology in Mediterranean mountain areas. Prof. García-Ruiz (Zaragoza, 1949) was lecturer, between 1974 and 1987, at the University of Cáceres and La Rioja. As staff Scientist and later Professor at the Spanish National Research Council (CSIC), he was Head of the Pyrenean Institute of Ecology (IPE-CSIC) (1987–1990) and Head of the Department of Global Change at the same institute, President of the Spanish Society of Geomorphology (1994–1996), besides a productive and tireless researcher. He has published more than 300 scientific articles, one third of them in international journals, and more than 35 books. He has participated in 40 research projects funded by the European Commission, Spanish and regional governments. With his enthusiasm and dedication he has inspired and encouraged a wide number of geographers and geomorphologists, including 10 PhD students and a great number of collaborators, most of them now working at different Universities and Research Centres around the world. ; Peer reviewed